Basophils and their mediators have long been thought to play an important role in allergic diseases. The overall objectives of this proposal are to understand the regulatory mechanisms by which human basophils are activated and recruited to sites of allergic reactions, and to understand how pharmacologic agents used for the treatment of chronic allergic disease interfere with these responses. We have hypothesized that the regulation of basophil recruitment occurs during margination, when circulating basophils adhere to vascular endothelium. To test this hypothesis, in vitro techniques for obtaining human basophils and culturing vascular endothelial cells will be used to determine the mechanisms regulating the adherence of basophils to endothelial cells. Studies are designed to establish which inflammatory agents act on endothelial cells to induce adhesiveness for basophils, and which agents promote basophil adhesiveness by an effect primarily on the basophil. In our attempts to identify relatively specific stimuli of basophil adherence, we have determined that IgE-dependent secretagogues and interleukin-3 selectively stimulate adhesiveness in basophils but not in neutrophils. By comparing their effects on neutrophils, additional studies will test whether other agents can stimulate basophil adhesiveness in a selective manner. We have established that indirect immunofluorescence and FACS analysis will permit the quantitative measurement of the expression of surface adherence glycoproteins (CD11/CD18) including Mo1, LFA-1, and p150,95 on basophils in both impure and highly pure preparations. We will expand preliminary studies suggesting that expression of these molecules may be altered in vitro during basophil activation. We will test a variety of inflammatory agents implicated in late phase allergic reactions, as well as biological fluids obtained from such reactions in allergic subjects, for their ability to activate basophils and promote basophil adherence to endothelial cells. We will determine whether changes in basophil CD11/CD18 expression and altered adhesiveness occurs during allergic reactions in vivo, and during seasonal exacerbations of allergic disease. Since several effective pharmacologic agents for the treatment of chronic allergic disease block the accumulation of inflammatory cells that occurs during the late phase allergic response, studies are planned to test the hypothesis that these agents interfere with basophil recruitment by altering basophil activation and adherence to endothelium. We will investigate the effect of a variety of anti-allergic medications in vitro on basophil adhesiveness and adherence glycoprotein expression. To determine the effect of anti-allergic medications in vivo, basophils will be obtained before and after administration of these drugs and basophil adhesiveness and adherence glycoprotein expression will be compared. It is anticipated that these studies will add to our knowledge of how basophils are recruited to sites of allergic reactions, and may suggest new ways of altering this response so as to alleviate the clinical manifestations of chronic allergic disease.